Concurrent wireless/landline interface apparatus and method

ABSTRACT

An apparatus for interfacing at least one landline telephone service, at least one wireless cellular-type telephone service, at least one cellular-type wireless telephone and at least one standard telephonic type communication device through standard building interior telephone cable.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.09/727,738, filed on Feb. 20, 2001, which is a continuation ofapplication Ser. No. 09/325,087, filed on Jun. 3, 1999, which is acontinuation of application Ser. No. 08/309,845, filed on Sep. 20, 1994,and now U.S. Pat. No. 5,946,616.

BACKGROUND AND PRIOR ART

The present invention relates to a system which integrates a standardtelephonic type communication device, a cellular-type wireless service,a cellular interface system such as described in U.S. Pat. No.4,658,096, issued Apr. 14, 1987 to West et al., existing telephonewiring installed within a building, and a telephone company wirelineservice. In particular, the standard telephonic type communicationdevice, when connected to the invention, is capable of selectively bothreceiving and initiating calls over the cellular type wireless serviceas well as also both receiving and initiating calls over the telephonecompany wireline service.

Known cellular interface products such as the Telular Phonecell™,PCS^(one)™, of Telular Corporation, Buffalo Grove, Illinois, andcompeting products from other companies, had difficulty in beingconnected to one or more telephone extensions located in other areas ofa building remote from the interface. The Telular PCS^(one)™ Systemshown pictorially in FIG. 1, is a combination charging circuit anddocking station for hand-held cellular transceivers such as the MotorolaMICRO-TAC transceiver which allows the coupling of a standard telephonetype communication device, such as a facsimile, modem, plain oldtelephone (POT) or any other device that would normally be coupled to astandard telephone wall jack. Connection of more than one telephoneextension at separate locations within the building disadvantageouslyrequired that separate wiring be installed in the building or required atrained installer to rewire the existing installed telephone wiring of abuilding, often with unsatisfactory results. After this installation orrewiring effort, two single line standard telephones were necessary toaccess both the telephone company and cellular-type service (cellular).A two line telephone would be required if a single instrument would beused to access both the telephone company (telco) wireline service aswell as the cellular interface line. When an incoming or outgoing callwould occur, there was often confusion as to whether the telco serviceor the cellular service was being accessed.

In addition, with the known cellular interface a consumer often made amistake in the installation of this type of product by not reading themanual and incorrectly plugging the cellular interface directly into thetelco service line. This was in violation of Federal CommunicationsCommission (FCC) Part 68 rules and invited possible damage to thecellular interface and to the telco equipment. Known cellular interfaceswere difficult to be installed by individuals possessing no technicalknowledge of electricity or of the telephone system. Each building isdifferent as to whether it has telco line 1 wiring installed, telco line2 wiring installed, wiring shorts between wires on telco line 1 or line2, an active Telco line 1, or an active Telco line 2. Because of allthese variables, there was difficulty for the consumer to effectivelyand consistently be able to properly install a known cellular interfacein a dwelling without a large number of consumer problems, and perhapssignificant numbers of damaged cellular interface devices. Prior artinterfaces lacked adaptive intelligence and system diagnostics to sensethe unique environment into which it was installed and properly react toit. Although prior art cellular interfaces allowed a standard telephonictype communication device to be connected to cellular service, prior artinterfaces disadvantageously did not allow a standard telephonic typecommunication device to be selectively switched between wireline andcellular service. Prior art interfaces had no provision for connectionto a wireline telephone company service.

This invention is directed at solving these and other disadvantages ofthe prior art.

OBJECTS OF THE INVENTION

An object of the invention is to allow a facility, normally wired for asingle telephone line from the wireline telephone company, to become atwo-line facility, with the second line coupled to a wirelesscommunication system and remain fully compatible with all FCC Part 68devices, including standard telephones, (both, single and double line),facsimile devices, alarm systems and modems.

Another object of the invention is to allow a consumer without any toolsor knowledge of a telephone system to use the invention by easilyallowing him to use his standard house telephone wiring and add acellular communication capability as an additional line to his currentsystem without improperly coupling an active device to a landlinetelephone outlet.

SUMMARY OF THE INVENTION

Accordingly, in accordance with an illustrative embodiment of thepresent invention, there is provided a telephonic communication systemhaving at least one communication device for interconnection with atelephone network via at least two communication media, the improvementcomprising means for coupling the at least one communication device withthe at least two communication media, and means for individuallydetermining the availability of each of the at least two communicationmedia, and means responsive to the determining means connected to thecoupling means for automatically interconnecting the at least onecommunication device with the telephone network via the available one ofthe communication media.

In accordance with another illustrative embodiment of the presentinvention, there is provided a communication system having first andsecond communication paths and at least one telephonic typecommunication device, the system being coupled to at least twocommunication networks for providing a first and second means ofcommunication, said first means of communication coupled to the firstcommunication path, and the communication system having at least onemeans for coupling the at least one telephonic communication type deviceto said first communication path, the improvement being means betweensaid at least one telephonic type communication device and said couplingmeans for connecting said telephonic type communication device to saidsecond communication path, and switching means coupled to said secondcommunication path and to said first and second means of communicationfor selectively coupling said second communication path to one of saidfirst and second means of communication.

In accordance with yet another illustrative embodiment of the presentinvention, there is provided a communication system having acommunication path and at least one telephonic type communicationdevice, the communication system being coupled to a communicationnetwork for providing a means of communication, and the communicationsystem having at least one telephonic communication type device coupledto said communication path, the improvement being testing means coupledto said communication path for testing the presence of any signalthereon, and interface means coupled to said communication path and saidtesting means and being responsive to said testing means for couplingsaid communication path to said communication network.

In accordance with still another illustrative embodiment of the presentinvention, there is provided a communication system comprising acellular type interface coupled between a cellular-type transceiver anda six position wall jack coupling means with at least four positionshaving individual conductors coupled thereto, a telephonic type devicecoupled to at least two of said individual conductors, and means coupledbetween said telephonic type device and said six position telephone jackcoupling means for inverting the position of at least two of saidindividual conductors to the position of two of the other individualconductors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial diagram of a prior art cellular interfaceconnected to a standard telephonic type communication device.

FIG. 2 is a simplified pictorial prior art diagram of a wirelinetelephone company central office, a customer's building having fourconductor wireline telephone company cabling installed therein, and asingle line telephonic type communication device connected to two of thefour conductors.

FIG. 3 is a simplified diagram showing the connection of the inventionand of two standard telephonic type communication devices.

FIG. 4 is a block diagram of a prior art cellular interface.

FIG. 5 is a block diagram of the invention.

FIG. 6A is a detailed schematic diagram of the invention.

FIGS. 6B-6J are detailed schematic diagrams of portions of FIG. 6Acorresponding to blocks of FIG. 5.

FIG. 7 is a flow chart showing the operation of the invention includingthe testing of the wireline telephone company's lines duringinitialization.

FIG. 8 is a state diagram showing the operation of the invention ascontrolled by software.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to FIG. 2, a building 130 has been wired with a fourconductor cable 160 for distributing a wireline telephone companyservice to a location within the building. The location has a sixposition telephone jack terminating the wireline telephone companyservice. FIG. 2 shows only one six position telephone jack 127 at onlyone location for simplicity; however, the building 130 has a pluralityof locations, each position has a six position telephone jack 127 suchas an RJ-11 jack for wireline telephone service termination. The servicefrom the wireline telephone company central office 104 is via a twoconductor cable 152 having a tip 154 and a ring 156 conductor. The tip154 and ring 156 conductors from the central office 104 are connected toa service entrance terminal block 158. The four conductor cable 160 ofthe building 130 is connected to the terminal block 158. Two conductors118 and 120 (usually with red and green wire insulation) of the fourconductors of the building cable are connected to the tip 154 and ring156 conductors from the central office 104. The other two conductors 122and 124 (usually with black and yellow wire insulation), althoughconnected to the service entrance terminal block 158, are not used forcommunication with the central office 104 if the building has onlysingle telephone line service, such as a typical single familyresidential dwelling. In addition to being connected to the serviceentrance terminal block 158, the yellow 124 and black 122 wires are alsoconnected to a “line 2” position of the 6 position telephone jack 127 ateach termination of wireline telephone service within the building 130.Therefore, the black 122 and yellow 124 conductors (ie line 2) of thebuilding telephone cable 160 are available for interconnection betweenthe invention and a plurality of standard telephonic type communicationdevices, each device normally capable of being coupled to a telco line(hereinafter “telephonic device”). The invention is simultaneouslyconnected to both wireline and cellular services. The invention ishoused in a docking station similar to the PCS^(one)™ presently beingmanufactured by Telular Corporation.

Referring now to FIG. 3, the installation of the invention starts bydirectly plugging the invention 132 into an available, typically wallmounted, six position telephone jack 127 via leads 128A-128D. The powersupply is connected to the system, and the power plug of the powersupply is plugged into an available power outlet. All pre-installedsingle line telephone devices are unplugged from the wall telephonejacks, a line inversion adapter 130 with leads 103A, 130B, is insertedinto the telephone jack 127, and each single telco line telephone device108 is plugged into the line inversion adapter 130 or conversely, one ormore telephone devices can also be left as pre-installed, via leads128A, 128B, as shown in FIG. 3. Single line standard telephonic typecommunication devices are designed to be plugged into the “line 1”position of six position telephone jacks. The line inversion adaptercauses the device to be connected to “line 2” of the telephone jack. Atelephone device 108 which is dedicated to the telco line does not usethe inversion adapter 130 at the wall telephone jack 127.

Upon being installed, the invention will perform a set of systemdiagnostics to determine if there are any problems with the installationenvironment. Determination of the electrical environment includes but isnot limited to: sensing if the unit telephone receptacle is connected tothe external wiring; sensing if the external wiring has a functioningconnection to a central office on Line 1; sensing it the external wiringhas a functioning connection to a central office on Line 2; and sensingwhether standard telephone devices are connected to Line 2. Systeminstallation problems are displayed as codes on a display of a portablecellular telephone placed in the docking station of the housing.Interpretation of these error codes is in a user's manual.

Upon performing an installation successfully, calls can be received andplaced on both the telco service and cellular service. Placing anoutgoing call is accomplished normally by picking up the telephonereceiver and dialing. The invention has different sets of criteria whichcan be used to determine whether it will default to the telco service orto cellular service. The criteria will vary depending on how the unit ismarketed and the service/customer which the unit is expected to serve.For example, an internal electronic clock/calendar allows the defaultingto depend upon the time of day and day of week in order to takeadvantage of differing telephone rates.

When a receiver of a telephone device is taken off hook with theinvention set to default to the telco service, and the user wants toplace a call on the cellular service, the user enters the cellular code,preferably **C. The invention then switches the telephone from the telcoline to the cellular line. An outgoing call is then placed normally. Ifthe unit defaults to the cellular service and the user wishes to place acall on the telco service, the user enters the telco code, preferably**T. The call is then placed normally.

An incoming call on the telco line rings normally and is answered byjust picking up the receiver. An incoming call on the cellular line hasa slightly different ring characteristic (preferably it is two burstsduring the two second ring period followed by a four second off time).Because the telephone rings with these two different characteristics,the person answering the call can tell in advance which line is ringing.If a call is received on the telco line and is answered and shortlythereafter a call is received on the cellular line, a call waiting beepis heard in the telephone receiver. If the person using the telephoneperforms a hook flash on the switch-hook of the telephone instrument,the telco line is placed on hold by the invention and the cellular lineis connected to the telephone instrument. If a hook flash is againperformed on the switch-hook of the telephone, the telco line isreconnected and the cellular line is placed on hold. The same sequenceof events applies if the initial call is received on the cellular lineinstead of the telco line. If a call is in progress on the cellular lineand a telco line call is being received (as evidenced by the telco lineringing,) a beep is heard through the telephone receiver. A hook flashputs the cellular line on hold and connects the telco line. The portionof the operation of the invention not fully disclosed herein isdescribed in the aforesaid U.S. Patent to West et al., which is herebyincorporated by reference.

TABLE 1 Event Name General Description. Off Hook Receiver of POTS devicehas been taken off the hook. Hang Up Receiver of POTS device has beenplaced on the hook. DialTone Dial tone has been detected on the telcoline. No Dial Tone No dial tone has been detected on the telco line.Telco Ring Detected the POTS device ringing from incoming telco call. NoTelco Ring POTS device stopped ringing from incoming telco call. CelAlert Incoming call from the cellular radio. Digit Entry Digits enteredfrom the POTS device. Dial Complete Outgoing caller has completeddialing. Cel Code Sequence of digits (**C) to switch from telco line tocel line. Telco Code Sequence of digits (**T) to switch from cel line totelco line. Lost Telco The telco line has lost its connection. HookFlash Momentary pressing (hang up) of POTS device receiver hook. Cel NotInuse The called party on the cellular line has hung up.

The Off Hook event as described in Table 1 is detected by monitoringloop current on either the telco line or the cellular line depending onwhich is switched in. (The cellular line is normally switched in.) Thisis done by software stored in Read Only Memory (ROM) internal to amicroprocessor detecting an active low signal on the Telco LC (U3 portP3.0) when on a telco line, or Cel LC (U3 port P3.5) when on a cellularline. The software does not recognize an off hook event unless loopcurrent had been absent (on hook) for more than 700 msec and then loopcurrent became present for at least 500 msec. The software switches theinvention from the cellular line to the telco line through hardware (U3port P.1 FIG. 6A), where cellular line is active high, and telco line isactive low.

The Hang Up event as described in Table 1 is detected by monitoring loopcurrent on either the telco line or the cellular line depending on whichis switched in. This is done by software detecting an active low signalon the Telco LC (U3 port P3.0, FIG. 6A) when on telco line, or Cel LC(U3 port P3.5) when on cellular line. Software does not recognize a HangUp event unless loop current had been present (off hook) for more than500 msec and then an absence of loop current occurred for at least 700msec.

The Dial Tone event as described in Table 1 is detected by softwaremonitoring the hardware dial tone input at U3, port P3.7, FIG. 6A.Software must look for a sequence of transitions on this port thatrepresent a pattern created by a superimposed 350 Hz with 440 Hz signalproduced by zero crossing detection. Software does not recognize theDial Tone Event unless this signal is present for at least 500 msecwhile the Off hook condition is true and connected to the telco line(active low asserted on U3, port P2.1. FIG. 6A).

The No Dial Tone event as described in Table 1 is detected by softwaremonitoring the hardware dial tone input at U3 port P3.7, FIG. 6A.Software must look for a sequence of transitions on this port thatrepresent a pattern created by a super imposed 350 Hz with 440 Hzsignal. Software does not recognize the No Dial Tone Event unless thereis an absence of this signal for at least one second while the Off hookcondition is true and connected to the telco line.

The Telco Ring event as described in Table 1 is detected by softwaremonitoring the hardware signal input at U3 port P3.4, FIG. 6A. Softwarerecognizes the Telco Ring Event by transitions on this port produced bya the ring signal (between 15 and 65 Hz) for at least 100 msec.

The No Telco Ring event as described in Table 1 is detected by softwaremonitoring the hardware signal input at U3 port P3.4, FIG. 6A. Softwaredoes not recognize the No Telco Ring event, unless the Telco Ring eventhas first been detected. When the Telco Ring event is detected, the NoTelco Ring event may be detected by the absence of the ring signal at U3port P3.4 for at least 5 seconds.

The Cel Alert event as described in Table 1 is detected by softwarereceiving a cell alert message from the cellular telephone via serialtransmission.

The Cel Alert, the Digit Entry event, and the Dial Complete event arewell known in the prior art.

The Cel Code event as described in Table 1 is detected by softwarerecognizing a sequence “**C” dialed.

The Telco Code event as described in Table 1 is detected by softwarerecognizing a sequence “**T” dialed.

The Lost Telco event as described in Table 1 is detected by the softwareof the invention. The software recognizes a telco connection byasserting an active high on the hardware telco hold line through U3,port P2.0, FIG. 6A and checking that telco loop current is present(active low on input U3, port P3.0). If telco loop current is notpresent after software asserts an active hold, then software detects theLost Telco condition.

The Hook Flash event as described in Table 1 is detected by monitoringloop current on either the telco line or the cellular line depending onwhich is switched in. This is done by software detecting an active lowsignal on the Telco LC (U3 port P3.0, FIG. 6A) when on the telco line,or Cel LC (U3 port P3.5) when on cellular line. Software does notrecognizes the Hook Flash event unless loop current had been present(off hook) for more than 500 msec and then an absence of loop currentoccurred for at least 200 msec, but no more than 700 msec.

The Cel Not Inuse event as described in Table 1 is detected by softwarereceiving the message from the cellular radio via serial transmissionand is well know in prior art.

The prior-art system shown in FIG. 4 interfaces a cellular telephone 212to a telephonic device 108 and it allows the telephonic device 108 toaccess communications via the cellular transceiver 212. The inventionconnects to a cellular transceiver 212 via a cellular telephoneinterface 204. The cellular telephone interface 204 is the actualphysical connection which interfaces the cellular telephone 212 to theinvention, and also connects to a telephonic device 108 via 208 thetelco line interface. All the necessary information and power to thecellular transceiver is received and/or supplied through the cellulartelephone interface 204.

Once power is applied to the invention, communication is establishedbetween the cellular transceiver 212 and the CPU interface 201. It usesa microprocessor, preferably an Intel 8051 type, to perform all itsoperations such as initializing the cellular transceiver 212, settingall of the control signals (I/O s) to their initial states for a ringercircuit 203, and a receive and transmit circuit 206. The software iswritten in 8051 assembly language. All functions of the unit iscontrolled by CPU interface 201. The CPU interface 201 communicates withthe cellular transceiver 212 via 204 and controls the necessary hardwareon board. This initializing is started by the Watchdog Timer & Resetcircuit 200 which is the circuit that jump starts the operation of allthe intelligence embedded into the system, it will restart the operationof all the intelligence if it detects an improper state of the externalhardware and/or internal timing sequences. During initialization, theCPU interface 201 sets all the necessary I/Os of the microprocessor totheir default conditions required by the external hardware to functionproperly. The telephone interface 208 is preferably an FCC part 68compatible RJ-11. At this point, if the telephonic device 108 connectedto the telephone interface 208 were to be taken offhook a precisionstandard dial tone would be received by the telephonic device.

If a call were to be made using the telephonic device 108 the followingwould take place:

When telephonic device 108 connected at telephone interface 208 comesoffhook, a Battery Voltage circuit 210 provides the necessary powerrequired to operate the telephonic device 108. Since the telephonicdevice 108 receives power, its offhook state will be detected by anonhook & offhook detect circuit 207. It detects the Onhook/Offhookcondition of the telephonic device 108. This circuit also allows the CPUinterface 201 to evaluate pulse dialing activity.

Onhook offhook detect circuit 207 will report this condition of thetelephonic device 108 to the CPU interface 201. Once CPU interface 201acknowledges the offhook condition it will generate a precision dialtone and inject it to receive and transmit circuitry 206. It interfacesthe receive and transmit signals from the telephonic device 108 to thereceive and transmit circuitry of the cellular transceiver 212 in orderto notify the telephonic device 108, that it can initiate dialingactivity.

Upon reception of dial tone, digits can be dialed in two differentformats:

First, DTMF (dual tone multi frequency) commonly known as touch-tonedialing, in which case the tones will be inputted to a DTMF detectioncircuit 202 via the receive and transmit circuit 206. The DTMF detectioncircuit will evaluate the digits dialed and determine their values, andrelay this information to the CPU interface 201.

Second, Pulse dialing which is an older method of dialing activity, willbe detected by the onhook & offhook detect circuitry 207. The digitinformation will then be relayed to the CPU interface 201.

The CPU interface 201 will take the digit signals received and willconvert them into serial digital information that could be understood bythe cellular transceiver 212. Once converted, the information will berelayed to the cellular transceiver 212 with the appropriate commandwhich will allow the cellular transceiver 212 to access the cellularservice provider through cell site 100 in order to establish acommunications link with the called party.

When the called party answers the call, a communications path will beestablished. The data or voice information between the telephonic deviceand the called party will be relayed by the receive and transmit audiocircuit 206.

This established link can be terminated two ways:

First, the called party can hang up. This is usually referred to as theremote hang up. In this case the cell site 100 will notify the cellulartransceiver 212, and the cellular transceiver will relay the informationto the CPU interface 201. Upon receiving this information the CPUinterface 201 will simply set all the external circuitry as if a hang upoccurred at the local telephonic device 108.

Second, the calling party hangs up. This is usually referred to as thelocal hang up. In this case the CPU unit 201 is informed by the onhook &offhook detection circuit 207 that the telephonic device 108 has beenhung up. The CPU interface 201 will in turn relay this message bysending an appropriate “end of call” message that is valid for theparticular cellular transceiver 212.

If a call were to be received by the cellular telephone interface unitthe following would take place:

The cellular transceiver 212 would be notified by the cell site 100 thatit is being paged by the cellular communication system. This messagewill be relayed to the CPU interface 201, which in turn will activatethe ringer circuit 203. Once the CPU informs this circuit that there isan incoming call, the unit will ring a telephonic device 108 connectedto the telephonic interface 208. This ringer signal is then injected tothe telephonic device 108 via telephonic interface 208. The telephonicdevice 108 will ring and the user would have to take the telephonicdevice 108 offhook. Upon noticing that the telephonic device 108 hasbeen taken offhook, the onhook & offhook detect circuit 207 will notifythe CPU interface 201 which then will send the appropriate call answermessage for the communication device in use, thereby enabling acommunications link with the calling party.

A power generation circuit 209 supplies the necessary power for thecellular transceiver 212 to function. The power from the powergeneration circuit 209 is relayed to the cellular transceiver 212 viacellular transceiver interface 204.

Referring now to FIG. 8, there is shown the state diagram of theinvention. An Initialize State 800 is in effect when the system is resetor initially turned on. During the Initialize State 800, communicationlines are monitored to verify that appropriate connections exist inorder to support product functionality. If the connections are correct,an Idle State 802 becomes active. If the connections are not correct, orsome non recoverable error occurs, then a Fatal Error State 801 becomesactive.

The Idle State 802 is the main state that occurs when the system isready and waiting for some event to occur. Events that will initiate aresponse while in the Idle State 802 are: the incoming Telco Ring event,the Off Hook from the POTS device event, and the incoming Cel Alertevent. The Telco Ring event will cause a Transition to a Ring Wait State803. The Off Hook event will connect the telco line and cause atransition to the Off Hook State 804. The Cel Alert event will connectthe cellular line and cause a transition to a Cel Alert State 811.

The Off Hook State 804 becomes active whenever the Off Hook event occursfrom the Idle State 802. While in the Off Hook State 804, the systemchecks for the presence of a telco dial tone from the telephone companyindicated by the Dial Tone event and the No Dial Tone event. If thesystem detects the telco dial tone, a transition is made to a Telco DialState 805. If, however, the Dial Tone event is not detected, the systemconnects the cellular line, generates a cel dial tone (differentiatedfrom the telco dial tone), and then transitions to a Cel Dial State 806.

The Telco Dial State 805 represent a condition where the system isconnected to the telco line, and the telephonic device is off hook.While in this state 805, the system will monitor and respond to one ofsix events: The Cel Alert event, the Digit Entry event, the DialComplete event, the Cel Code digit entry event, the Lost Telcoconnection event, and the Hang Up event. If the Cel Alert is detected,the system will momentarily connect the cellular line, sound a beep, andthen connect back to the telco line indicating to the user that there isan incoming call on the cellular line. If the Digit Entry is detected,the digit pressed is stored by the system in a digit buffer. If thedigit buffer contains the appropriate digits (such as **C), or if theLost Telco connection is detected, the system is then connected to thecellular line, the Cel Dial Tone is generated, and a transition is madeto the Cel Dial State 806. If the Dial Complete event occurs, indicatingthat the user has finished dialing, then a transition is made into aTelco Talk State 807. The Hang Up event will simply cause a transitionback to the Idle State 802. Any time a transition is made into the TelcoDial State 805 or the Cel Dial State 806, the digit buffer is cleared.The Cel Dial State 806 represents a condition where the system isconnected to the cellular line, and the POTS device is off hook. Whilein this state 806, the system will monitor and respond to one of sixevents: The Cel Alert event, the Digit Entry event, the digit DialComplete event, the Telco Code digit entry event, the Telco Ring event,and the Hang Up event. If the Cel Alert or the Dial Complete isdetected, the system will initiate a cellular send command andtransition to a Cel Talk State 808. If the Digit Entry is detected, thedigit pressed is stored by the system in the digit buffer. If the digitbuffer contains the appropriate digits (such as **T), the system is thenconnected to the telco line, and a transition is made to the Telco DialState 805. If the Dial Complete event occurs, indicating that the userhas finished dialing, then a transition is made into a Cel Talk State808. If the Telco Ring event occurs, the system will sound a beepindicating that an incoming call has been detected on the telco line.The Hang Up event will simply cause a transition back to the Idle State802.

The Telco Talk State 807 represents a state where a connection toanother party has been established on the telco line. This may occureither through an incoming call from the Ring Wait State 803, or throughan ongoing call from the Telco Dial State 805. While in the Telco TalkState 807, the system will monitor and respond to one of four events:The Hang Up event, the Lost Telco connection event, the Cel Alert Event,and the hook Flash Event. The Hang Up event will simply cause atransition back to the Idle State 802. If the Lost Telco connection isdetected, the system will connect the cellular line and check to see ifthere is a complete entry in the digit entry buffer meaning a number hadbeen dialed as an outgoing call. If the digit entry is complete, theentry is redialed on the cellular line and a transition is made to theCel Dial State 806. However, if a complete entry does not exists in thebuffer, then the transition is made to the Cel Dial State 806 and thecel dial tone is generated. If the Hook Flash event occurs, the telcoline is put on hold by the system, the cellular line is then connected,and a transition is made to a Telco Wait Cel Dial State 809. If the CelAlert is detected, the system will momentarily connect the cellularline, sound a beep, and then connect back to the telco Line and thencause a transition to a Telco Talk Cel Alert State 810.

The Cel Talk State 808 represents a state where a connection to anotherparty has been established on the cellular line. This may occur eitherthrough an incoming call from the Cel Alert State 811, or through anongoing call from the Cel Dial State 806. While in the Cel Talk State808, the system will monitor and respond to one of four events: The HangUp event, the Telco Ring event, the digit entry event, and the HookFlash Event. The Hang Up event will simply cause a transition back tothe Idle State 802. The Digit Entry event will be audibly produced orechoed to the user. If the Telco Ring event is detected, the system willsound a beep indicating an incoming call on the telco line andtransitions to Cel Talk Telco Ring State 815. If the Hook Flash eventoccurs, the telco line is then connected, and a transition is made to aCel Wait Telco Dial State 812.

The Cel Wait Telco Dial State 812 represents a state where a connectionto another party has been established on the cellular line, and the userhas done a hook flash to dial out on the telco line without losing thecellular party. Therefore, this state 812 will respond to only one oftwo events: The Digit Dial Complete event for dialing another party, andthe Hang Up event. The Hang Up event will simply cause a transition backto the Idle State 802. The Dial Complete event will cause a transitionto a Telco Talk Cel Wait State 813.

The Telco Wait Cel Dial State 809 represents a state where a connectionto another party has been established on the telco line, and the userhas done a hook flash to dial out on the cellular line without losingthe telco line party. Therefore, this state 809 will respond to only oneof three events: The Dial Complete event for dialing another party, theCel Alert event, and the Hang Up event. The Hang Up event will simplycause a transition back to the Idle State 802. If the Dial Complete orthe Cel Alert events occur, the system will initiate a send command andwill cause a transition to a Cel Talk Telco Wait State 814.

The Telco Talk Cel Alert State 810 represents a state where a connectionto another party has been established on the telco line, and the CelAlert has occurred. In this state 810, the system will respond to theHook Flash event, the Hang Up event, and the Cel not Inuse event. TheHang Up event will cause a transition to the Cel Alert State 811. TheCel not Inuse event will cause a transition back to the Telco Talk State807. If the Hook Flash is detected, the system will put the telco lineon hold, connect the cellular line, and make a transition into the CelTalk Telco Wait State 814.

The Cel Talk Telco Ring State 815 represents a state where a connectionto another party has been established on the cellular line, and theTelco Ring event has occurred. In this state 815, the system willrespond to the Hook Flash event, the Hang Up event, the Digit Entryevent, the Lost Telco event, and the Telco Ring event. The Hang Up eventwill cause a transition to the Ring Wait State 803. If the hook Flash isdetected, the system connects the telco line, and makes a transitioninto the Telco Talk Cel Wait State 813. If the Telco Ring is detected,the system will sound a beep. If the Lost Telco connection occurs, atransition is made into the Cel Talk State 808. The Digit Entry eventwill cause the digit to be echoed on the telephonic device.

The Telco Talk Cel Wait State 813 represents a condition where the telcoline is connected with an active party, and there is also a partywaiting on the cellular line. In this Telco Talk Cel Wait state 813, thesystem will respond to the Hook Flash event, the Cel Not Inuse Event,and the Hang Up event. If the Hook Flash occurs, the telco line isplaced on hold, the cellular line is reconnected, and a transition tothe Cel Talk Telco Wait State 814 is made. If the Cel not Inuse eventoccurs, a transition is made to the Telco Talk State 807. If the Hang Upevent occurs, the system will reconnect the cellular line, begin ringingin order to re-establish connection with the party waiting on thecellular line, and make a transition to the Cel Alert State 811.

The Cel Talk Telco Wait State 814 represents a condition where thecellular line is connected with an active party, and there is also aparty holding on the telco line. In this state 814, the system willrespond to the Hook Flash event, the Lost Telco Event, and the Hang Upevent. If the Hook Flash occurs, the telco line connected and releasedfrom hold, and a transition to the Telco Talk Cel Wait State 813 ismade. If Lost Telco connection event occurs, a transition is made to theCel Talk State 808. If the Hang Up event occurs, the system will leavethe cellular line connected, begin ringing in order to re-establishconnection with the party waiting on the telco line, and make atransition to the Ring Wait State 803.

The Ring Wait State 803 represents a condition where the telephonicdevice is hung up and ringing due to a party on the telco line. This canoccur because there is an incoming call on the telco line, or becausethere is a previous party waiting on the telco line after hanging up onthe cellular line through the Cel Talk/Telco Wait State 814. While inthis state 803, the system will respond to the No Telco Ring event bymaking a transition back to the Idle State 802. The system will alsorespond to the Off Hook event by connecting the telco line (which may ormay not be connected already), and releasing a potential hold, and thenmaking a transition to the Telco Talk State 807.

The Cel Alert State 811 represents a condition where the telephonicdevice is hung up and ringing due to a party on the cellular line. Thiscan occur because there is an incoming Cel Alert, or because there is aprevious party waiting on the cellular line after hanging up on thetelco line through the Telco Talk Cel Wait State 813. While in thisstate 811, the system will respond to the Cel not Inuse event by makinga transition back to the Idle State 802. The system will also respond tothe Off Hook event by making a transition to the Cel Talk State 808.

The Fatal Error State 801 is state where the system has determined thata non-recoverable error condition exists. In this state 801, the systemmust be turned off and/or reset. This state 801 may be potentiallyentered from any state capable of detecting a fatal error condition.

An Off Hook Timeout State 816 can occur any time the telephonic deviceis left unattended and in the off hook position. If this conditionoccurs in certain states, this state 816 will become active. While inthis state 816, the only event that is allowed is the Hang Up eventwhich causes a transition back to the Idle State 802.

Referring to FIG. 5, a Voltage Detect Circuit 400 is shown in block formin FIG. 5 and shown in detail in FIG. 6B; it detects unwanted DCvoltages on communication path 2 prior to connecting the interfacecircuit to the path. The voltage detect circuit 400 detects unwanted DCvoltages by placing a capacitance across the tip and ring ofcommunication path 2. To determine if an unwanted voltage is present,the capacitance is allowed to charge from the unwanted voltage andsubsequently discharge, on command from the microprocessor U3, through aoptically isolated sensing network. The sensing network develops a logicsignal input to CPU 201 indicating the presence or absence of voltage.Referring now to FIG. 6B, the circuit consists of resistors 1-5, diodes7 and 8, capacitor 6, transistor 11, and opto-isolators 9 and 10. Thefunction is as follows:

The tip 128-C and ring 128-D of communication path 2 are connected toinputs T2 (FIG. 3) and R2 of the circuit 400 shown in block form in FIG.5 and shown in detail in FIG. 6B. Resistors 4 and 5 form a voltagedivider across the tip and ring. Capacitor 6 is connected across 4 and 5through steering diodes 7 or 8 respectively. The conducting diode isdetermined by the polarity of any voltage present between the tip andring for communication path 2. Capacitor 6 charges through theconducting steering diode to one-half the open circuit talk batteryvoltage. The microcontroller U3 (FIG. 6A) polls the charge state of thecapacitor by generating a logic high (+5 VDC) from U3 P2.2 to transistor11 through current limiting resistor 1. This forces transistor 11 intoconduction, resulting in the flow of current from the +12 VDC supply,through current limiting resistor 2, and the LED (terminals 2&4) ofopto-isolator 10. The phototransistor of opto-isolator 10 conducts dueto current flow in the associated LED, allowing capacitor 6 to dischargethrough current limiting resistor 3 and the LED (terminals 4&2) ofopto-isolator 9. Current flowing in the LED of 9 forces the associatedphototransistor to conduct, placing GROUND on P2.3 input ofmicroprocessor U3. The microcontroller software polls the state of theinput to determine the presence of talk battery on communication path 2.If the pin state is logic high (+5 VDC), no talk battery is present. Ifthe state is logic low (GROUND), talk battery is present on the path.

A communication path switching circuit 406, shown in block form in FIG.5 connects a Part 68 telephonic type device to multiple communicationmedia systems i.e. to a telephone line or to a cellular system interfaceof the invention. The communication path switching circuit 406, shown indetail in FIG. 6C, consists of relay 12, a transistor 13, a currentlimit resistor 14, and a diode 15. The Part 68 telephonic deviceterminals are connected to the contacts 12A-12F of relay 12. Contacts12A-12C switch one terminal of the Part 68 device between communicationpath 1 and the cellular interface. Contacts 12D, 12E, & 12F switch theother terminal. Control of relay 12 is accomplished by a signal frommicroprocessor U3 (FIG. 6A). A logic high (+5 VDC) from U3 P2.1 isapplied to transistor 13 through current limiter 14. Transistor 13conducts upon application of the logic high, allowing current to flowthrough the coil of relay 12, changing the state of the relay andconnecting the Part 68 device to the cellular interface. A logic low(GROUND) from U3 P2.1 cuts 13 off, terminating the coil current of 12,allowing the relay to change state and connecting the Part 68 device tocommunication path 1.

A loop current detection circuit 410, shown in block form in FIG. 5,detects the presence of loop current flowing on communication path 1.This circuit 410 shown in detail in FIG. 6D provides an electricallyisolated logic signal to microprocessor U3 (FIG. 6A) indicating anon-hook or off-hook condition for the Part 68 device when connected tothe central office via path 1. The loop current detection circuit 410consists of pullup resistor 16 and opto-isolator 17. The circuitfunctions as follows: The loop current path between communication path 1and the Part 68 telephonic device flows through the bi-directional LED(terminals L1 & T1) of opto-isolator 17. The presence of loop current(off-hook condition) forces the phototransistor in 17 to conduct,placing a logic low (GROUND) on input P3.0 of microcontroller U3. Theabsence of loop current (on-hook condition) cuts off the phototransistorof 17, placing a logic high (+5 VDC) via 16 on U3 P3.0.

A DTMF (Dual Tone Multi Frequency) detection circuit 420, shown in blockform in FIG. 5, couples DTMF from communication path 2 (either by loopvoltage or loop current variations) for processing by microprocessor U3.The components of the DTMF Detection Circuit 420, shown in detail inFIG. 6E, consists of a DTMF decoder 18, clamp diodes 19 and 20, limitingresistors 21 and 25, DC blocking capacitors 22 and 24, and transformer23. Transformer 23 is a 1:1 isolation transformer with 600 ohm primaryand secondary impedances. The primary of 23 is connected across the tipand ring (T2 & R2) of communication path 2 through capacitor 24. DTMFenergy present on communication path 2 is coupled through 24 totransformer 23 primary and across 23 to the secondary. From transformer23 secondary the isolated DTMF energy is routed to the DTMF decoder 18via resistor 25 for processing.

A dial tone detection circuit 430, shown in block form in FIG. 5,provides an electrically isolated signal to the microprocessor U3 (FIG.6A) for the purpose of determining the presence of a dial tone signal.As shown in detail in FIG. 6F, the circuit 430 consists of resistors26-28, and a comparator 29. A sample of the audio signal oncommunication path 2 is conveyed to the inverting input of comparator 29(pin 6) from 18, previously discussed. When the audio signal atcomparator 29 pin 6 exceeds the threshold established by voltage dividerresistors 26 and 27 at comparator 29 pin 5, the output of 29 (pin 7)changes state from a logic high (+5 VDC) to a logic low (GROUND). In thecase of dial tone audio, the logic signal takes on the form of aperiodic pulse train. These logic state changes are conveyed to U3 inputP3.7 for processing by the microprocessor software.

A ring signal detection circuit 440, shown in block form in FIG. 5,detects the presence of a ring signal voltage or current oncommunication path 1, originating in the central office, and it providesan isolated logic level to the microcontroller indicating the occurrenceof a ringing event. As shown in detail in FIG. 6G, the components of theRing Signal Detection Circuit 440 consists of resistors 30-34, acapacitor 35, an opto-isolator 36, and comparator 37. The circuitfunctions as follows: The Central Office ringing signal is coupled fromcommunication path 1 via R1 through current limiting resistor 31, DCblocking capacitor 35, the bi-directional LED (terminals 1&2) of 36, andreturning via T1. Application of the ringing signal to 36 causes the LEDto illuminate forcing the associated phototransistor to conduct. Theconducting phototransistor places a ground at the inverting input ofcomparator 37 pin 9 forcing the output of 37 pin 8 to a logic high (+5VDC). The termination of the central office ringing signal cuts off theLED illumination of 36, forcing the phototransistor into anon-conducting state, and placing +5 VDC on pin 9 of 37 via pull-upresistor 30. This condition results in a logic low (GROUND) output frompin 8 of 37. The logic states indicating the presence/absence of ringingsignals are conveyed to microprocessor U3, input P3.4 (FIG. 6A) forprocessing by the microprocessor software.

A ringer detection circuit 450, shown in block form in FIG. 5, tests todetermine if a Part 68 telephonic device has been connected tocommunication path 2. Testing is accomplished by placing a test ringingsignal on the path and observing the presence of current flow in thepath due to the signal and a connected Part 68 device. The presence orabsence of the Part 68 device is transmitted to the microcontroller as alogic signal. As shown in detail in FIG. 6H, the ringer detectioncircuit 450 consists of resistors 38-46, clamp diodes 47 and 48, acomparator 49, a solid state relay 50 and a transistor 51. The circuitfunctions as follows: A test ringing signal is generated by block 203,described previously, and applied to the communication path 2. If anon-hook, Part 68 telephonic device is connected to the path, the ringingsignal forces current to flow through resistor 46, solid state relay 50,to the connected Part 68 device and the ringer signal generator 203 viaCR. Solid state relay 50 is closed and shunts 43 & 44 due to a U3 P3.2microcontroller signal applied through 40, 41 and 51. A voltage developsacross 46 due to the ringer current flow and is applied to the invertinginput (pin 2) of comparator 49 via resistor 45 and clamp diodes 47 & 48.The application of voltage to 49 forces the device output at pin 1 to alogic low state (GROUND). The output of comparator 49 pin 1 is input tothe microprocessor U3 at input P3.5 (FIG. 6A) for processing. Removal ofthe ringing signal, or the lack of an on-hook Part 68 device connectedto the path, forces 49 to a logic high state (+5 VDC).

A call hold circuit 470, shown in block form in FIG. 5, continues loopcurrent flow through the normal communication path 1 while the Part 68telephonic type device is disconnected from the normal communicationpath 1 and connected to cellular interface. As shown in detail in FIG.61, the call hold circuit consists of resistors 52 and 53, a transistor54, a diode 55, and a relay 56. Microprocessor U3 (FIG. 6A) generates alogic high (+5 VDC) at P2.0. This signal is applied to transistor 54,via current limiting resistor 52, forcing 54 to conduct. Conductingtransistor 54 causes current to flow through the armature coil of relay56, closing the associated contacts. The contact closure forces loopcurrent from communication path 1 to flow through terminating resistor53 via L1 & R1. With communication path 1 terminated in this manner, thePart 68 telephonic device may be connected to cellular interface withoutterminating a call in progress on communication path 1. A logic low(GROUND) at U3 P2.0 terminates the relay 56 closure condition.

A battery control voltage circuit 480, shown in block form in FIG. 5,enables or disables the generation of voltages supplied to the Part 68telephonic type device loop circuit. As shown in detail in FIG. 6J, thebattery control voltage circuit consists of resistors 57 and 58, atransistor 59, and a solid state relay 60. The circuit enables ordisables cellular interface talk battery generation as follows: A logicsignal from microprocessor U3 P3.1 controls the operation of thecircuit. The logic signal is applied to transistor 59 via current limitresistor 57. A logic high (+5 VDC) turns 59 on, closing solid staterelay 60 at terminals 4 & 6. The relay closure allows the application of−50 VDC, generated by previously described block 210 at VB, to the Part68 device. A logic low at U3 P3.1 opens relay 60 terminals 4 & 6,terminating the battery voltage connection.

The system control flow from a power on condition to a normal runningcondition is depicted by FIG. 7. A Start condition 701 is shownindicating the start of control flow from the power on condition. First,software guarantees that the talk battery control voltage is turned off(even though this is the default hardware state) by writing an activelow to U3, port P3.1 (FIG. 6A) indicated by process block 702.

After the talk battery control voltage is turned off, the software flowproceeds to process block 703, to test the outer telco pair. The outertelco pair is determined to be active if an active high is detected bysoftware on U3, port P2.3, after software holds U3, port P2.2 (FIG. 6A)high. Software does not hold U3, port P2.2 high before pulsing it threetimes, and then holding it low, in order to discharge any potentialfloating capacitance on the line. Software then proceeds to check if theouter pair is active indicated by decision block 704. A process block705 is executed if the outer telco pair is active in order to display anerror message through the radio, at which time, the software proceeds tothe Fatal Error state 706. While in the Fatal Error state 706, thesystem must be re-powered. If, however, the outer telco pair is detectedas being inactive, then the talk battery voltage is turned on indicatedby process block 707. Then software proceeds to process block 708.

The process block, item 708 indicates a software test to ensure that atleast one standard telephonic type communication device is correctlyconnected. This is done through software by applying an active high toU3, port P3.2 (FIG. 6A) to turn on ring voltage, then applying a 20 Hzsignal to U3, port P1.5 and detecting a 20 Hz signal at U3, port P3.5.After software does this check, the ring voltage is turned off (activelow on U3, port P3.2). If the 20 Hz signal is detected, then it isassumed that at least one standard telephonic type communication deviceis correctly connected. Then software proceeds through a decision block,item 709, to process block 711. If, however, there is no standardtelephonic type communication device signal seen, then softwareindicates this through the radio display 710, and loops back to theprocess block 708 until at least one standard telephonic typecommunication device is correctly connected.

When it is determined that the outer telco pair is inactive and at leastone standard telephonic type communications device is correctlyconnected, software proceeds to the process block 711 to test that theinner telco pair is active. Software recognizes a telco inner pairconnection by asserting an active high on the hardware telco hold linethrough U3, port P2.0 and checking that telco loop current is present(active low on input U3, port P3.0). If telco loop current is notpresent (through decision block 712), then an error message is displayedthrough the display of the cellular telephone indicated by process block713. Then, the software proceeds directly to an idle state 714.

While a detailed description of the preferred embodiment of theinvention has been given above, it should be appreciated that manyvariations can be made thereto without departing from the spirit andscope of the invention as set forth in the appended claims. Thisinvention is not limited for use in buildings have a four conductorinternal telephone cable. The invention can be used in buildings havingany greater number of conductors in its internal telephone cable, aslong as one pair of conductors (or one internal communication channel)is not in use or can be freed from use. Furthermore, the disclosureassumes the internal telephone cable of the building is comprised ofdiscrete metallic conductors, with a pair of conductors forming acommunication path; however, it is foreseen that the internal telephonecable of the building can be coaxial, fiber optic, wireless or any otherform of communication path. In addition, there is no requirement in thisdisclosure that there be a one-to-one correspondence between internalbuilding telephone communication channels and conductors of a cable. Itis foreseen that the invention also works with any type multiplexing oftelephone channels on a single communication path.

What is claimed is:
 1. In a cellular interface unit for coupling a land-type telephone instrument to a cellular radio system, which interface unit comprises interface means for coupling the land-type telephone instrument to a cellular radio transceiver for providing the capability of using the land-type telephone instrument for making or receiving calls over a cellular radio system, the improvement comprising: premises land-line wiring connection means for connecting said interface means to premises land-line wiring of a landline telephone network, which premises land-line wiring has a first wireline thereof capable of being connected to the landline telephone network, and a second wireline thereof capable of being connected to the landline telephone network, which premises land-line wiring has tip and ring terminals for each of the first and second wirelines; said means for connecting comprising means for coupling said interface means to tip and ring terminals of a premises second wireline.
 2. In a cellular interface unit for coupling a land-type telephone instrument to a cellular radio system, which interface unit comprises interface means for coupling the land-type telephone instrument to a cellular radio transceiver for providing the capability of using the land-type telephone instrument for making or receiving calls over a cellular radio system, the improvement comprising: premises land-line wiring of a landline telephone network, said premises land-line wiring having a first wireline thereof capable of being connected to the landline telephone network, and a second wireline thereof capable of being connected to the landline telephone network, each of said first and second wirelines having tip and ring terminals; said cellular interface unit comprising premises land-line wiring connection means for connecting said interface means to one of said first and second wirelines of said premises land-line wiring; said premises land-line wiring means comprising means coupling said interface means to said tip and ring terminals of said one of said first and second wirelines of said premises land-line wiring. 